Scanned laser light source

ABSTRACT

The thermal processing device includes a stage, a continuous wave electromagnetic radiation source, a series of lenses, a translation mechanism, a detection module, a three-dimensional auto-focus, and a computer system. The stage is configured to receive a substrate thereon. The continuous wave electromagnetic radiation source is disposed adjacent the stage, and is configured to emit continuous wave electromagnetic radiation along a path towards the substrate. The series of lenses is disposed between the continuous wave electromagnetic radiation source and the stage, and are configured to condense the continuous wave electromagnetic radiation into a line of continuous wave electromagnetic radiation on a surface of the substrate. The translation mechanism is configured to translate the stage and the line of continuous wave electromagnetic radiation relative to one another. The detection module is positioned within the path, and is configured to detect continuous wave electromagnetic radiation.

RELATED APPLICATIONS

This application is a division of Ser. No. 11/079,785, filed Mar. 14,2005 and now allowed, which is a division of Ser. No. 10/325,497, filedDec. 18, 2002 and now issued as U.S. Pat. No. 6,987,240, which is acontinuation-in-part of Ser. No. 10/202,119, filed on Jul. 23, 2002 andnow issued as U.S. Pat. No. 7,078,119, which is a continuation-in-partof Ser. No. 10/126,419, filed Apr. 18, 2002 and now issued as U.S. Pat.No. 7,005,601, all four of which are incorporated herein by reference.This application is also related to Ser. No. 11/522,179, filed Sep. 15,2006 and now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to semiconductor device manufacturing.More particularly, the invention is directed to an apparatus and methodfor thermally processing a substrate by scanning the substrate with aline of radiation.

2. Description of Related Art

The integrated circuit (IC) market is continually demanding greatermemory capacity, faster switching speeds, and smaller feature sizes. Oneof the major steps the industry has taken to address these demands is tochange from batch processing multiple substrates, such as siliconwafers, in large furnaces to single substrate processing in smallreaction chambers.

Generally, there are four basic operations performed in such batchprocessing fabrication, namely layering, patterning, doping, and heattreatments. Many of these operations require heating the substrate tohigh temperatures so that various chemical and physical reactions cantake place. Of particular interest are heat treatments and layering,each of which will be discussed below.

Heat treatments are operations in which the substrate is simply heatedand cooled to achieve specific results. During heat treatment noadditional material is added to or removed from the substrate. Heattreatments, such as rapid thermal processing or annealing, typicallyrequire providing a relatively large amount of thermal energy (hightemperature) to the substrate in a short amount of time, and thereafterrapidly cooling the substrate to terminate the thermal process. Theamount of thermal energy transferred to the substrate during suchprocessing is known as the thermal budget. The thermal budget of amaterial is a function of temperature and the duration of the process. Alow thermal budget is desired in ultra-small IC manufacturing, which canonly be provided at high temperature if the time of the process is veryshort.

Examples of heat treatments currently in use include rapid thermalprocessing (RTP) and impulse (spike) annealing. While thermal processesare widely used, current technologies are not ideal. Such technologiestend to ramp up and ramp down the temperature of the substrate tooslowly, in addition to exposing the substrate to elevated temperaturesfor long periods. These problems become more severe with increasingsubstrate sizes, increasing switching speeds, and/or decreasing featuresizes.

In general, these heat treatments raise the substrate temperature undercontrolled condition according to a predetermined thermal recipe. Thethermal recipes fundamentally consist of: a temperature that thesubstrate must be heated to; the rate of change of temperature, i.e.,the temperature ramp-up and ramp-down rates; and the time that thethermal processing system remains at a particular temperature. Forexample, thermal recipes may require the substrate to be heated fromroom temperature to distinct temperatures of 1200° C., or more, forprocessing times at each distinct temperature ranging up to 60 seconds,or more.

Moreover, to meet certain objectives, such as minimal diffusion ofdopants in the substrate, the amount of time that each substrate issubjected to high temperatures must be restricted. To accomplish this,the temperature ramp rates, both up and down, are preferably high. Inother words, it is desirable to be able to adjust the temperature of thesubstrate from a low to a high temperature, and vice versa, in as shorta time as possible so as to minimize the thermal budget.

This requirement for high temperature ramp rates led to the developmentof rapid thermal processing (RTP), where typical temperature ramp-uprates range from 200-400° C./s, as compared to 5-15° C./minute forconventional furnaces. Typical ramp-down rates are in the range of80-150° C./s.

FIG. 1 is a graph 100 of thermal profiles of different prior art thermalprocesses. As can be seen, the thermal profile 102 of a typical RTPsystem has a 250° C./s ramp-up rate and a 90° C./s ramp-down rate.

A drawback of RTP is that it heats the entire substrate even though theIC devices reside only in the top few microns of the substrate. Theheating of the entire substrate limits how fast one can heat up and cooldown the substrate. Moreover, once the entire substrate is at anelevated temperature, heat can only dissipate into the surrounding spaceof structures. As a result, today's state of the art RTP systemsstruggle to achieve 400° C./s ramp-up rates and 150° C./s ramp-downrates.

FIG. 1 also shows a thermal profile 104 of a laser annealing process.Laser annealing is used during the fabrication of thin film transistor(TFT) panels. Such systems use a laser spot to melt and recrystallizepolysilicon. The entire TFT panel is exposed by scanning the laser spotacross successive exposure fields on the panel. For substrateapplications a laser pulse is used to illuminate an exposure field for aduration of approximately 20-40 ns, where the exposure field is obtainedby rastering across and down the substrate. As can be seen from thethermal profile 104 for laser annealing, the ramp rate is nearlyinstantaneous at billions of degrees per second. However, the laserpulse or flash used for laser annealing is too fast and often does notprovide enough time for sufficient annealing to occur for non-meltprocesses. Also, devices or structures next to the exposed regions mayeither be exposed to extreme temperatures causing them to melt, or totemperatures that are too low resulting in too little annealing. Stillfurther, homogenization of the thermal exposure of each portion of thesubstrate is difficult to attain because different regions adsorb heatat different rates resulting in huge temperature gradients. The processis too fast for thermal diffusion to equilibrate temperature, therebycreating severe pattern dependencies. As a result, this technology isnot appropriate for single-crystal silicon annealing because differentregions on the substrate surface may be heated to vastly differenttemperatures causing large non-uniformities over short distances.

Another thermal processing system currently in development by VortekIndustries LTD., of Canada, uses flash assisted spike annealing toattempt to provide a high thermal energy to the substrate in a shortamount of time and then rapidly cool the region to limit the thermalexposure. Use of this thermal processing system should give the junctiondepth of a spike anneal to 1060° C. but improve the activation withflash to 1100° C. Typically, the RTP system ramps up to the desiredtemperature typically around 1060° C. and then begins to ramp downimmediately after having reached the desired flash temperature. This isdone to minimize the amount of diffusion that takes place while stillgetting suitable activation from the elevated temperature. The thermalprofile 106 of such a flash assisted spike anneal is also shown in FIG.1.

In view of the above, there is a need for an apparatus and method forannealing a substrate with high ramp-up and ramp-down rates. This willoffer greater control over the fabrication of smaller devices leading toincreased performance. Furthermore, such an apparatus and method shouldensure that every point of the substrate has a substantially homogenousthermal exposure, thereby reducing pattern dependencies and potentialdefects.

We now turn our attention to layering, which is another basicfabrication operation that typically requires the addition of energy orheat. Layering adds thin layers or films to a substrate's surface usinga variety of techniques, of which the most widely used are growing anddeposition. The added layers function in the IC devices assemiconductors, dielectrics (insulators), or conductors. These layersmust meet various requirements, such as uniform thickness, smooth andflat surfaces, uniform composition and grain size, stress-free films,purity, and integrity. Common deposition techniques that require theaddition of energy are: chemical vapor deposition (CVD); a variation ofCVD known as rapid thermal chemical vapor deposition (RTCVD); anothervariation of CVD known as low pressure CVD (LPCVD); and atomic layerdeposition (ALD), to name but a few.

CVD is the most widely used technique for physically depositing one ormore layers or films, such as silicon nitride (Si₃N₄), on a substratesurface. During the CVD process, various gases, such as ammonia (NH₃)and dichlorosilane (DCS), containing the atoms or molecules required inthe final film, are injected into a reaction chamber. Chemical reactionsbetween the gases are induced with high energy such as heat, light, orplasma. The reacted atoms or molecules deposit on the substrate surfaceand build up to form a thin film having a predetermined thickness. Thedeposition rate can be manipulated by controlling the reaction conditionof supplied energy; the amount and ratio of gases present in thereaction chamber; and/or the pressure within the reaction chamber.

The reaction energy is typically supplied by heat (either conduction orconvection), induction RF, radiant, plasma, or ultraviolet energysources. Temperatures typically range from room temperature to 1250° C.,and more typically from 250° C. to 850° C.

Although it is desirable in current CVD thermally driven processes toheat the substrate to a high temperature, it is also desirable that thesubstrate is not exposed to these high temperatures for too long.However, current thermally driven processes heat the entire substrate,despite the fact that only the surface of the substrate needs to beheated. Heating the entire substrate limits how fast one can heat up andcool down the substrate, as the substrate has a thermal inertia thatresists changes in temperature.

Furthermore, in CVD and LPCVD, various gases are supplied or injectedinto the reaction chamber at the same time. A gas phase reactionoccurring between the reactant gases may, however, occur at any locationwithin the reaction chamber, including the ambient space around thesubstrate. Reactions occurring in the ambient space are undesirable asthey can form particles which can become imbedded in the film formed onthe substrate.

More recently, ALD was developed to address the above described gasphase reaction problems with CVD and LPCVD. In ALD, the first and secondgases are not present in the reaction chamber at the same time,therefore, the gas phase reaction does not occur in the ambient space.This eliminates the problems associated with particle formation in theambient space. However deposition rates for ALD are slow, takingapproximately 1 Angstrom per second. Also, ALD is bound by the sametemperature constraints and thermal budget issues as CVD.

In light of the above, there is a need for an apparatus and method fordepositing layers on a substrate that reduces gas phase reactionproblems. More specifically, such an apparatus and method, should onlyheat the surface of the substrate and provide high ramp-up and ramp-downrates, i.e., low thermal budget. Such an apparatus and method preferablymeet general and specific parameters, such as uniform layer thickness,smooth and flat layer surfaces, uniform layer composition and grainsize, low stress films, purity, and integrity.

SUMMARY OF THE INVENTION

According to an embodiment of the invention there is provided anapparatus for depositing layers on a substrate. The apparatus includes areaction chamber and a gas injector to inject at least one gas into thereaction chamber. The apparatus also includes a continuous waveelectromagnetic radiation source, a stage within the reaction chamber,and focusing optics disposed between the continuous wave electromagneticradiation source and the stage. The stage is configured to receive asubstrate thereon. The focusing optics are configured to focuscontinuous wave electromagnetic radiation from the continuous waveelectromagnetic radiation source into a line of continuous waveelectromagnetic radiation on an upper surface of the substrate. The lineof continuous wave electromagnetic radiation preferably extends acrossthe width or diameter of the substrate. The apparatus further includes atranslation mechanism configured to translate the stage and the line ofcontinuous wave electromagnetic radiation relative to one another.

Further according to the invention there is provided a method fordepositing one or more layers on a substrate. The substrate is initiallypositioned in the reaction chamber. One or more gases are introducedinto the reaction chamber. A predetermined speed for translating a lineof radiation is determined. This predetermined speed is based on anumber of factors, such as a thermal recipe for processing thesubstrate, the properties of the substrate, a power of the continuouswave electromagnetic radiation, a width of the line of radiation, apower density at the line of radiation, or the like.

Continuous wave electromagnetic radiation is then emitted from acontinuous wave radiation source and preferably collimated. Thecontinuous wave electromagnetic radiation is subsequently focused into aline of radiation extending across the surface of the substrate. Theline of radiation is then translated relative to the surface at theconstant predetermined speed.

The combination of the introduced gas(s) and heat generated by the lineof radiation causes at least one gas to react and deposit a layer on thesurface of the substrate. Undesirable byproducts of the reaction arethen flushed from the reaction chamber. This process is repeated until alayer having a predetermined thickness is formed on the surface of thesubstrate.

According to another embodiment of the invention there is provided athermal flux processing device. The thermal flux processing deviceincludes a continuous wave electromagnetic radiation source, a stage,focusing optics, and a translation mechanism. The continuous waveelectromagnetic radiation source is preferably one or more laser diodes.The stage is configured to receive a substrate thereon. The focusingoptics are preferably disposed between the continuous waveelectromagnetic radiation source and the stage and are configured tofocus continuous wave electromagnetic radiation from the continuous waveelectromagnetic radiation source into a line of continuous waveelectromagnetic radiation on an upper surface of the substrate. A lengthof the line of continuous wave electromagnetic radiation preferablyextends across an entire width of the substrate. The translationmechanism is configured to translate the stage and the line ofcontinuous wave electromagnetic radiation relative to one another, andpreferably includes a chuck for securely grasping the substrate.

Still further, there is provided a method for thermally processing asubstrate. Continuous wave radiation is focused into a line of radiationat an upper surface of the substrate.

The line of radiation is translated relative to the surface at aconstant predetermined speed. This allows for every point of thesubstrate to have a substantially homogenous thermal exposure orhistory. Process control is achieved by modulating scan speed ratherthan lamp power, thereby simplifying the control of the apparatus. Thisallows for highly local heating without generating defects.

Therefore, the present invention heats only a small portion of thesurface of the substrate at any given moment. This reduces the totalradiated power requirement. In fact, an energy density of 150 kW/cm² isachievable on a 300 mm substrate with only a 5 kW radiation source, asonly one chord of the substrate is heated at any one time.

By heating a small area at any given moment, it is possible to achievemillions of degrees per second ramp rates on a substrate with only a fewkilowatts of radiated power. Additionally, ramp rates this high allowfor the upper surface to be heated from ambient temperature to 1200° C.or higher and cooled back down to nearly ambient temperature before thebulk substrate temperature can rise.

The above described apparatus and method can heat the substrate surfaceto any reasonable temperature for a millisecond or less. In addition, asthe line of radiation only applies heat to the surface of the substrate,the reaction of the gases only occurs at the surface. Where thereactions at room temperature are negligible, this allows multiple gasesto be injected simultaneously without leading to undesirable gas phasereactions away from the substrate surface. This method can be performedat atmospheric pressure, resulting in faster decomposition of reactants,thereby enabling high deposition rates.

According to another embodiment of the invention, a thermal processingthat includes a stage, a continuous wave electromagnetic radiationsource, a series of lenses, a translation mechanism, a detection moduleand a computer system. The stage is configured to receive a substratethereon. The continuous wave electromagnetic radiation source isdisposed adjacent the stage, and is configured to emit continuous waveelectromagnetic radiation along a path toward the substrate. The seriesof lenses is disposed between the continuous wave electromagneticradiation source and the stage. The series of lenses are configured tocondense the continuous wave electromagnetic radiation into a line ofcontinuous wave electromagnetic radiation on a surface of the substrate.Condensing causes the radiation to converge or concentrate on or towardthe line of continuous wave electromagnetic radiation. The translationmechanism is configured to translate the stage and the line ofcontinuous wave electromagnetic radiation relative to one another. Thedetection module is positioned within the path, and is configured todetect continuous wave electromagnetic radiation. In a preferredembodiment, the detection module is positioned between the series oflenses, more preferably between the expander lens and the remainder ofthe lenses that are configured to condense the continuous waveelectromagnetic radiation. The computer system is coupled to thedetection module. Also in a preferred embodiment, the line of continuouswave electromagnetic radiation is no wider than 500 microns and has apower density of at least 30 kW/cm².

The detection module preferably comprises at least one emitted powerdetector configured to detect emitted continuous wave electromagneticradiation emitted from the continuous wave electromagnetic radiationsource. The detection module also preferably comprises at least onereflected power detector configured to detect reflected continuous waveelectromagnetic radiation reflected from the surface. At least one beamsplitter is provided for sampling a portion of the emitted continuouswave electromagnetic radiation module and the stage, and more preferablybetween the series of lenses, more preferably between the expander lensand the remainder of the lenses that are configured to condense thecontinuous wave electromagnetic radiation. In one embodiment, theemitted power detector and the reflected power detector detectcontinuous wave electromagnetic radiation at 810 nm. At least onetemperature detector is configured to detect the temperature of thesurface at the line of continuous wave electromagnetic radiation bydetecting continuous wave electromagnetic radiation at a wavelengthother than 810 nm. A filter is preferably disposed between thetemperature detector and the line of continuous wave electromagneticradiation. The filter is configured to allow only continuous waveelectromagnetic radiation having a wavelength other than 810 nm to reachthe temperature detector. The filter is configured to allow opticalpyrometer operation between 900 nm and 2000 nm, and particularly at 1500nm.

The computer system preferably includes procedures for determiningemitted power that is emitted to the emitted power detector; proceduresfor determining reflected power that is reflected to the reflected powerdetector; and procedures for controlling power supplied to thecontinuous wave electromagnetic radiation source based on the detected,emitted, and/or reflected power. The computer system may also includereflectivity procedures for determining reflectivity. Reflectivity isproportional to the reflected power divided by the emitted power. Thecomputer system may also include temperature procedures for determininga temperature of the surface at the line of continuous wave radiation.The temperature is proportional to an adsorbed power which equals theemitted power less the reflected power.

The series of lenses preferably include at least one expander lensdisposed between the continuous wave electromagnetic radiation sourceand the stage. The at least one expander lens is configured to expand abeam of continuous wave electromagnetic radiation emitted from thecontinuous wave electromagnetic radiation source into an expanded beamof continuous wave electromagnetic radiation. The series of lenses mayfurther include multiple cylindrical lenses arranged in series betweenthe continuous wave electromagnetic radiation source and the stage. Themultiple cylindrical lenses are configured to focus the expanded beam ofcontinuous wave electromagnetic radiation into a line of continuous waveelectromagnetic radiation on the surface of the substrate.

The continuous wave electromagnetic radiation source comprises multiplesets of opposing laser diode modules, where each of the multiple sets ofopposing laser diode modules are preferably controlled separately. Also,a separate detection module is preferably provided for each set of laserdiodes.

An interleave combiner is preferably disposed between the continuouswave electromagnetic radiation source and the series of lenses. Theinterleave combiner preferably uses dielectric stacks for enhancedreflection at continuous wave electromagnetic radiation wavelength. Athermal emission signal from the substrate is preferably measuredthrough the series of lenses as well as the interleave combiner at awavelength longer than that of the continuous wave electromagneticradiation. The interleave combiner utilizes fill ratio enhancing opticsto reduce the size of the series of lenses.

An adjustment mechanism may also be provided to move the continuous waveelectromagnetic radiation source and the stage towards one another. Thisallows the computer system to control the adjustment mechanism based onmeasurements taken by the detection module, in order to keep the line ofcontinuous wave radiation in focus on the surface. In an alternativeembodiment a reflective surface is provided for redirecting scatteredcontinuous wave radiation back towards the line of continuous waveradiation.

According to another embodiment of the invention, a thermal processingmethod is provided. A surface of a substrate is heated with apredetermined power density for a predetermined length of time. Thisallows the surface of the substrate to be heated from an ambienttemperature (T_(A)) to a process temperature (T_(P)), while thetemperature at a predetermined depth (T_(D)) from the surface remainsbelow the ambient temperature, plus half the process temperature lessthe ambient temperature (T_(D)≦T_(A)±(T_(P)−T_(A))/2). In a preferredembodiment, the predetermined power density is at least 30 kW/cm², thepredetermined length of time is between 100 micro-seconds and 100milliseconds, the ambient temperature is less than about 500° C., theprocess temperature is more than about 700° C., and the predetermineddepth is 10 times a depth of interest, where the depth of interest is amaximum depth of device structures in silicon.

The thermal processing method may also include initially coating thesurface with a thermal enhancement layer. Also, any scattered continuouswave electromagnetic radiation may be reflected back toward the line ofradiation. The emitted power of the continuous wave electromagneticradiation and the reflected power of continuous wave electromagneticradiation reflected from the surface may be measured. The reflectedpower may then be compared to the emitted power. Power supplied to thecontinuous wave electromagnetic radiation source may be controlled basedon such a comparison. Also, a separate measurement may be taken ofthermal emission from the substrate at a focus of the line of continuouswave electromagnetic radiation. The temperature may be determined at thesurface at the line. Also, the absorption, reflectivity, and emissivitymay be determined.

Before focusing, an optimum orientation of the substrate relative to ascan direction may be chosen. The optimum orientation is determined byassuring scan direction to have a minimum overlap with principal slipplanes of the substrate. Also, the substrate may be pre-heated.Pre-heating comprises of one or more pre-scans with the continuous waveelectromagnetic radiation source, and is preferably performed using ahot plate.

Still further, according to the invention the series of lenses includeat least one expander lens and multiple cylindrical lenses. The expanderlens is disposed between the continuous wave electromagnetic radiationsource and the stage. The expander lens is configured to expand the beamof continuous wave electromagnetic radiation into an expanded beam ofcontinuous wave electromagnetic radiation. The multiple cylindricallenses are preferably arranged in series between the at least oneexpander lens and the stage. The multiple cylindrical lenses areconfigured to focus the expanded beam of continuous wave electromagneticradiation into a line of continuous wave electromagnetic radiation onthe surface of the substrate. The at least one expander lens preferablycomprises two expander lenses, while the multiple cylindrical lenseshave spherical figure or aspherical figure. Some of the multiplecylindrical lenses may have spherical figure and others may not. A gasinjector may be provided near the multiple lenses to circulate coolingpurge gas between the multiple lenses.

Further, an automatic focusing mechanism for a thermal processing deviceis provided. The automatic focusing mechanism includes a continuous waveelectromagnetic radiation module, a stage, at least one photo detector,a translation mechanism, an adjustment mechanism, and a controller. Thecontinuous wave electromagnetic radiation module is configured to focuscontinuous wave electromagnetic radiation into a line of continuous waveelectromagnetic radiation on a surface of a substrate. The stage isconfigured to receive a substrate thereon. The at least one photodetector is coupled to the stage. The at least one photo detector isconfigured to measure intensity of the continuous wave electromagneticradiation. The translation mechanism is configured to translate thestage and the continuous wave electromagnetic radiation module relativeto one another. The adjustment mechanism is coupled to the stage, and isconfigured to adjust the height, roll and pitch of the stage. Finally,the controller is coupled to the continuous wave electromagneticradiation module, the at least one photo detector, the translationmechanism, and the adjustment mechanism. The at least one photo detectorpreferably includes three photo detectors embedded into the stage. Thethree photo detectors and the controller are configured to measure apitch, roll, and height of the stage relative to the continuous waveelectromagnetic radiation module.

In use, the line of continuous wave electromagnetic radiation isautomatically focused on a surface of a substrate. After the automaticfocusing mechanism is provided, a tooling substrate having at least oneaperture there through, is positioned on the stage. The at least oneaperture aligns with the at least one photo detector. The at least oneaperture is then radiated with continuous wave electromagnetic radiationfrom the continuous wave electromagnetic radiation source. An intensityof the continuous wave electromagnetic radiation is then measured at theat least one photo detector, and a position of the stage and thecontinuous wave electromagnetic radiation source are adjusted relativeto on another, based on the intensity.

The stage and the continuous wave electromagnetic radiation source arethen translated laterally relative to one another to align anotheraperture in the tooling substrate with another photo detector. Anotheraperture is then exposed to continuous wave electromagnetic radiationfrom the continuous wave electromagnetic radiation source. Anotherintensity is then sensed of the continuous wave electromagneticradiation at another photo detector. Finally, a position of the stageand the continuous wave electromagnetic radiation source is set relativeto one another, based on the another intensity. These steps are repeateduntil the stage is in a predetermined position relative to thecontinuous wave electromagnetic radiations source.

Yet another embodiment provides a method for thermally processing asemiconductor substrate. Continuous wave electromagnetic radiation isfocused into a line of continuous wave electromagnetic radiationextending partially across a surface of a semiconductor substrate. Theline of continuous wave electromagnetic radiation and the surface isthen translated relative to one another at a constant predeterminedspeed. The line of radiation is subsequently shifted along its length adistance either equal to or slightly less than its length. The line ofcontinuous wave electromagnetic radiation and the surface is againtranslated relative to one another at the constant predetermined speed.This over-scanning allows every exposed point of the substrate to have asubstantially homogenous thermal exposure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of the invention,reference should be made to the following detailed description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a graph of thermal profiles of different prior art thermalprocesses;

FIG. 2A is a diagrammatic side view of an apparatus for thermallyprocessing a substrate, according to an embodiment of the invention.

FIG. 2B is a diagrammatic top view of the substrate an stage shown inFIG. 2A;

FIG. 3 is a diagrammatic side view of another apparatus for thermallyprocessing a substrate, according to another embodiment of theinvention;

FIG. 4 is a flow chart of a method for thermally processing a substrate;

FIG. 5 is a graph of the temperature at a fixed point on and through thesubstrate during thermal processing, according to an embodiment of theinvention;

FIG. 6 is a diagrammatic side view of an apparatus for depositing layerson a substrate, according to another embodiment of the invention;

FIG. 7 is a flow chart of a method for depositing layers on a substrate,according to the embodiment of the invention shown in FIG. 6;

FIG. 8 is a graph of the results of a Monte Carlo simulation for silanedecomposition at 850° C. and 740 Ton, according to the embodiment of theinvention shown in FIG. 6;

FIG. 9A is a side view of yet another apparatus for thermally processinga substrate, according to yet another embodiment of the invention;

FIG. 9B is an oblique view of the apparatus shown in FIG. 9A;

FIG. 9C is a rear view of yet another apparatus for thermally processinga substrate, according to yet another embodiment of the invention;

FIG. 10 is a diagrammatic side view of the interleave combiner shown inFIGS. 9A and 9B;

FIG. 11 is a more detailed sectional side view of the focusing opticsand the detection module shown in FIGS. 9A and 9B;

FIG. 12 is an isometric view of a prototype of the apparatus shown inFIGS. 9A and 9B;

FIG. 13 is a flow chart of a method for controlling a thermal process;

FIG. 14A is a partial sectional side view of an automated focusingmechanism;

FIG. 14B is a top view of the tooling substrate and stage shown in FIG.14A, as taken along line 14B-14B′;

FIG. 14C is a flow chart of a method for automatically focusing a lineof continuous wave electromagnetic radiation of an upper surface of asubstrate; and

FIG. 14D is a graph of the measured energy density versus the verticaldistance from best focus at an aperture.

Like reference numerals refer to corresponding parts throughout theseveral views of the drawings. For ease of reference, the firstnumber(s) of any reference numeral generally indicates the figure numberin which the reference numeral was first shown. For example, 102 can befound in FIG. 1, and 1341 can be found in FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2A is a diagrammatic side view of an apparatus 200 for thermallyprocessing a substrate, according to an embodiment of the invention.Thermally processing a substrate means conducting any thermal processthat requires the characteristics of the invention described below.Exemplary embodiments of such a thermal process include thermalannealing of substrates or thermal processes used in chemical vaporceposition (CVD), both of which will be described throughout theremainder of the Figures.

The apparatus 200 comprises a continuous wave electromagnetic radiationmodule 201, a stage 216 configured to receive a substrate 214 thereon,and a translation mechanism 218. The continuous wave electromagneticradiation module 201 comprises a continuous wave electromagneticradiation source 202 and focusing optics 220 disposed between thecontinuous wave electromagnetic radiation source 202 and the stage 216.

In a preferred embodiment, the substrate 214 is any suitable substrate,such as a single crystal silicon substrate; silicon on insulator (SOI);Silicon Germanium or alloys thereof; glass or quartz substrate with asilicon layer thereon, as used for manufacturing thin film transistors(TFT); or the like. It will, however, be appreciated that thermal fluxprocessing of single crystal silicon substrates is more difficult thanthat of TFT substrates, as single crystal silicon substrates have a muchhigher thermal conductivity than TFTs and the single crystal siliconsubstrates' applications require tighter control of the thermal process.

The continuous wave electromagnetic radiation source 202 is capable ofemitting “continuous waves” or rays of electromagnetic radiation, suchas light. By “continuous wave” it is meant that the radiation source isconfigured to emit radiation continuously, i.e., not a burst, pulse, orflash of radiation. This is quite unlike lasers used in laser annealing,which typically use a burst or flash of light.

Furthermore, as the continuous wave electromagnetic radiation needs tobe absorbed at or near the surface of the substrate, the radiation has awavelength within the range at which the substrate absorbs radiation. Inthe case of a silicon substrate, the continuous wave electromagneticradiation preferably has a wavelength between 190 nm and 950 nm. Morepreferably, it has a wavelength of approximately 810 nm.

Alternatively, a high power continuous wave electromagnetic radiationlaser source operation in or near the UV may be used. Wavelengthsproduced by such continuous wave electromagnetic radiation laser sourcesare strongly absorbed by most otherwise reflective materials.

In a preferred embodiment, the continuous wave electromagnetic radiationsource 202 is capable of emitting radiation continuously for at least 15seconds. Also, in a preferred embodiment, the continuous waveelectromagnetic radiation source 202 comprises multiple laser diodes,each of which produces uniform and spatially coherent light at the samewavelength. The power of the laser diode(s) is in the range of 0.5 kW to50 kW, but preferably approximately 5 kW. Suitable laser diodes are madeby Coherent Inc. of Santa Clara, Calif.; Spectra-Physics of California;or by Cutting Edge Optronics, Inc. of St. Charles, Mo. A preferred laserdiode is made by Cutting Edge Optronics, although another suitable laserdiode is Spectra Physics' MONSOON® multi-bar module (MBM), whichprovides 40-480 watts of continuous wave power per laser diode module.

The focusing optics 220 preferably comprise one or more collimators 206to collimate radiation 204 from the continuous wave electromagneticradiation source 202 into a substantially parallel beam 208. Thiscollimated radiation 208 is then focused by at least one lens 210 into aline of radiation 222 at an upper surface 224 of the substrate 214.

Lens 210 is any suitable lens, or series of lenses, capable of focusingradiation into a line. In a preferred embodiment, lens 210 is acylindrical lens. Alternatively, lens 210 may be one or more concavelenses, convex lenses, plane minors, concave minors, convex minors,refractive lenses, diffractive lenses, Fresnel lenses, gradient indexlenses, or the like. The focusing optics 220 is described in furtherdetail below in relation to FIG. 11.

The stage 216 is any platform or chuck capable of securely holding thesubstrate 214 during translation, as explained below. In a preferredembodiment, the stage 216 includes a means for grasping the substrate,such as a frictional, gravitational, mechanical, or electrical system.Examples of suitable means for grasping include mechanical clamps,electrostatic or vacuum chucks, or the like.

The apparatus 200 also comprises a translation mechanism 218 configuredto translate the stage 216 and the line of radiation 222 relative to oneanother. In one embodiment, the translation mechanism 218 is coupled tothe stage 216 to move the stage 216 relative to the continuous waveelectromagnetic radiation source 202 and/or the focusing optics 220. Inanother embodiment, the translation mechanism is coupled to both thecontinuous wave electromagnetic radiation source 202 and the focusingoptics 22 to move the continuous wave electromagnetic radiation source202 and/or the focusing optics 220 relative to the stage 216. In yetanother embodiment, the translation mechanism 218 moves the continuouswave electromagnetic radiation source 202, the focusing optics 220, andthe stage 216. Any suitable translation mechanism may be used, such as aconveyor system, rack and pinion system, or the like.

The translation mechanism 218 is preferably coupled to a controller 226to control the scan speed at which the stage 216 and the line ofradiation 222 move relative to one another. In addition, translation ofthe stage 216 and the line of radiation 222 relative to one another ispreferably along a path perpendicular to the line of radiation 222 andparallel to the upper surface 224 of the substrate 214. In a preferredembodiment, the translation mechanism 218 moves at a constant speed.Preferably, this constant speed is approximately 2 cm/s for a 35 micronwide line. In another embodiment, the translation of the stage 216 andthe line of radiation 222 relative to one another is not along a pathperpendicular to the line of radiation 222.

FIG. 2B is a diagrammatic top view of the substrate and stage, as takenalong line 2B-2B′ of FIG. 2A. In a preferred embodiment, the substrate214 is a circular substrate with a diameter of 200 or 300 mm, and athickness of approximately 750 microns. The line of radiation 222extends across the substrate 214. The line of radiation 222 alsopreferably has a width 228 of between 3 and 500 microns. In a preferredembodiment, the line of radiation 222 has a length that extends acrossthe entire diameter or width of the substrate and has a width 228 ofapproximately 35 microns. The width is measured at half the maximumintensity of the radiation (otherwise knows as Full Width Half Max(FWHM)). In all embodiments, the length of the line is longer than itswidth. In a preferred embodiment, the line of radiation 222 linearlytraverses the substrate 214, such that the line 222 is perpendicular tothe direction of the movement, i.e., the line 222 remains parallel to afixed line or chord 252 of the substrate that is perpendicular to thedirection of the movement at all times.

A preferred power density at the line of radiation is between 10 kW/cm²and 200 kW/cm² with a nominal range near 60 kW/cm². It is not readilyachievable to radiate the entire surface of a substrate at these powerdensities, but it is possible to scan across the substrate a line ofradiation that has this intensity. For example, an experiment using a400 microns wide line of radiation with a peak power density of 70kW/cm² scanned at 100 cm/s, heated the surface of a substrate toapproximately 1170° C. with ramp-up and ramp-down rates exceeding 4million° C./s.

FIG. 3 is a diagrammatic side view of another apparatus 300 forthermally processing a substrate, according to another embodiment of theinvention. This embodiment shows another arrangement of focusing optics320. In this embodiment, the focusing optics 320 comprise a lens 210 andone or more radiation guides, such as an optical fiber 308 and a prism306. Other radiation guides such as a waveguide, mirror, or diffuser mayalso be used.

Radiation from the continuous wave electromagnetic radiation source 202is directed at one or more prisms 306 which redirects the radiationtowards one or more optical fibers 308. Radiation is transmitted throughthe optical fibers 308 towards the lens 210, where it is focused into aline of radiation 222.

It will be appreciated that many different combinations of theaforementioned focusing optics 220 (FIG. 2A) or 320 may be used totransmit and focus the radiation from the continuous waveelectromagnetic radiation source into a line of radiation. Also, alinear array of laser diodes could be used as the radiation source 202.Any suitable means for producing a uniform radiation distribution, suchas a radiation diffuser, may be used in conjunction with the radiationsource 202.

FIG. 4 is a flow chart 400 of a method for thermally processing asubstrate 214 (FIG. 2A). An apparatus as described above in relation toFIGS. 2A, 2B, and 3 is provided at step 402. The controller 226 thendetermines, at step 404, the scan speed at which the line of radiation222 and the substrate will move relative to one another. Thisdetermination is based on the thermal recipe for processing thesubstrate; the substrate properties; the power of the continuous waveelectromagnetic radiation source; the width of the line of radiation;the power density at the line of radiation; or the like processcharacteristics.

The continuous wave electromagnetic radiation source 202 (FIG. 2A) emitsa continuous wave of radiation 204, at step 406. This radiation 204 ispreferably collimated into a collimated beam of radiation 208, at step408. The collimated beam of radiation 208 is focused into a line ofradiation 222, at step 410. In accordance with the predetermined scanspeed, the stage 216 and the line of radiation 222 are translated, atstep 412, relative to one another by the translation mechanism 218. Thetranslation is performed along a path perpendicular to the line ofradiation 222 and parallel to the upper surface of the substrate, suchthat the line of radiation traverses the entire substrate 214. In apreferred embodiment, the translation mechanism 218 scans the radiationsource and focusing optics over the upper surface of the substrate atapproximately 2 cm/s.

FIG. 5 is a graph 500 of the temperature versus time and depth at afixed point on and through the substrate during thermal processingperformed according to the method described above in relation to FIG. 4.A temperature axis 502 indicates a temperature of between 0 and 1400° C.at the fixed point. Axis 504 indicates a depth from the upper surface224 (FIG. 2B) into the substrate 214 (FIG. 2B) at the fixed point. Axis506 indicates the time in seconds at some point after the start ofscanning The fixed point is assumed to be located at 508.

As the line of radiation 222 (FIG. 2B) scans across the upper surface224 of the substrate 214, it subjects a line or chord on the substrateto the heat it generates. Before the line of radiation reaches the fixedpoint, the temperature at the fixed point, both at the upper surface 224and throughout a substrate cross-section at the fixed point, is ambienttemperature, as indicated by reference numeral 516. As soon as the lineof radiation reaches the fixed point at 508, the temperature at theupper surface ramps up to a process temperature, such as 1200° C. (orother desired temperature necessary for the process), at approximately10×106° C./s, as shown by reference numeral 510. At the same time, thesubstrate acts as a heat sink resulting in a dramatic drop-off intemperature away from the surface, as indicated by reference numeral512. For example, as shown in FIG. 5, at 0.04 cm from the point on theupper surface, the temperature is approximately 200° C. Thus, theheating effect is generally localized to the upper surface only. This isextremely advantageous, as generally only the regions near the uppersurface 224 of the substrate require thermal processing.

As the line of radiation passes over and away from the fixed point, thetemperature drops rapidly, as shown at reference numeral 514. Again,this is because the substrate acts as a heat sink diffusing the heat atthe upper surface throughout the remainder of the cooler substrate. Thisis not possible with prior art thermal systems, such as RTP, thatsimultaneously heat the entire substrate. In RTP, the entire substrateis subjected to an elevated temperature and, therefore, cannot easilydissipate the heat to a cooler region. In fact, no comparison can bemade to RTP on the time scale shown in FIG. 5, because a superimposedRTP graph would yield an almost flat plane at 1100° C. extending forabout one second. One second is 400 times greater than the time periodillustrated in FIG. 5.

Therefore, unlike prior art processes, the current invention can heat asubstrate 214 with a predetermined power density and for a shortpredetermined length of time (approximately 1 millisecond), such thatthe surface of the substrate 224 is heated from an ambient temperature(T_(A)) of preferably less than 500° C., to a process temperature(T_(P)) of preferably above 700° C. At the same time, the temperature atthe predetermined depth (Td) from the surface remains below the ambienttemperature, plus half the process temperature less the ambienttemperature, i.e., T_(D)<=T_(A)+(T_(P)−T_(A))/2. The predetermined depthis approximately ten times the depth of interest, i.e., ten times themaximum depth of device structures in Si. In a typical Si substrate, themaximum depth of the device structure is about 3 microns.

Transfer of heat to the bulk of the substrate promotes homogenousthermal exposure, as heat has enough time to diffuse from a locallystrong heat absorbing region to a lower heat absorbing region. Also,pattern density effects are comparable to RTP. Advantageously, the timescale is short enough to limit the diffusion depth of the heat transferto several microns, as opposed to the several hundred-micron thicknessof the substrate in a typical RTP, thereby greatly reducing the totalrequired power. Since the bulk of the substrate is not appreciablyheated, it provides an ideal heat sink for the temperature ramp down.

One concern of prior art laser annealing systems regards stress relateddefects caused by rapidly heating relatively small areas of a substrate.Therefore, experimentation was undertaken to test whether the thermalflux processing of the present invention causes any stress relateddefects in the substrate. Peak stress occurs near the max temperaturegradient, not the max temperature. If a line of radiation is suitablynarrow and the depth of heating suitably shallow, it is possible todisplace the region of maximum thermal gradient from the region ofhighest temperature, thereby increasing the slip window and decreasingdefects. During this experimentation, a sample was scanned at 20 cm/sunder a 400 micron wide line of radiation with a peak power density of60 kW/cm². The present invention was able to displace the peak thermalgradient from the peak temperature, thus enabling Ultra Shallow Junction(USJ) formation suitable for the 70 nm node with a 1 keV Boron implantwithout introducing any dislocations. Only the typical implant relateddefects were observed.

FIG. 6 is a diagrammatic side view of an apparatus 600 for depositinglayers on a substrate, according to another embodiment of the invention.The apparatus 600 is similar to the apparatus 200 shown in FIGS. 2A and2B, and apparatus 300 shown in FIG. 3. Components having the samereference numerals are the same as those shown in FIGS. 2A and 2B. Theapparatus 600 may also be used to perform deposition processes, such asCVD, ALD, or the like.

In addition to the components described above in relation to FIGS. 2A,2B and 3, apparatus 600 shows a reaction chamber 602, in which many ofthe components are housed. At least one injector 604 is used tointroduce or inject one or more gases 616 into reaction chamber 602. Thegas injector 604 preferably comprises one or more gas sources 612(1)-(N)fluidly coupled by ducts 610 to one or more gas inlets 608 in a gasmanifold 606. The gas injector 604 may be located at any suitablelocation within the reaction chamber 602. For example, gas may beinjected at the side of the reaction chamber and flow across the surfaceof the substrate orthogonally to the direction of relative motionbetween the line of radiation and the surface of the substrate, or gasmay be injected from above the substrate, as shown.

In the embodiment shown in FIG. 6, continuous wave electromagneticradiation is collimated by the collimator, redirected towards thesubstrate by the prism 306 and focused into a line 222 by the lens 210.It should, however, be appreciated that the focusing optics 220 maycomprise any suitable focusing optics capable of focusing a line ofenergy onto the upper surface 224 of the substrate 214, as describedabove. Further, it should be appreciated that the focusing optics may beplaced outside of the chamber, where radiation passes into the chambervia a transparent window. Still further, the chamber and/or gas sourcesmay take on any suitable shape and/or configuration.

FIG. 7 is a flow chart 700 of a method for depositing one or more layerson a substrate, according to the embodiment of the invention shown inFIG. 6. A substrate 214 is positioned in the reaction chamber 602, at702. One or more gases 616, such as ammonia (NH₃) and dichlorosilane(DCS), containing the atoms or molecules required in layer 614 are thenintroduced at 704 into the reaction chamber 602 containing the substrate214.

A predetermined speed for translating a line of radiation 222, asdescribed below, is determined at 706. This predetermined speed is basedon a number of factors, such as a thermal recipe for processing thesubstrate, the properties of the substrate, a power of the continuouswave electromagnetic radiation, a width of the line of radiation, apower density at the line of radiation, or the like. In a preferredembodiment, this predetermined speed is approximately 2 cm/s.

Continuous wave electromagnetic radiation is then emitted at 708 from acontinuous wave electromagnetic radiation source 202, as describedabove. The continuous wave electromagnetic radiation is preferablycollimated at 710 by the collimator 206.

The continuous wave electromagnetic radiation is subsequently focused at712 into a line of radiation 222 extending across the upper surface 224of the substrate. In a preferred embodiment, the width 228 of the lineof radiation is approximately 35 microns wide. The line of radiation isthen translated at 714 relative to the surface at the constantpredetermined speed, determined above. This translation is undertaken bythe translation mechanism 218 under control of the controller 226.

The combination of the introduced gas(s) 616 and heat generated by theline of radiation causes at least one gas 616 to react and deposit alayer 614 on the surface of the substrate. This reaction may be achemical reaction between gases, a decomposition of one or more gases,or the like. Undesirable byproducts of the reaction are then flushedfrom the reaction chamber at 716.

This process is repeated until a layer 614 having a predeterminedthickness is formed on the upper surface 224 of the substrate 214. Thepredetermined scan speed is preferably faster than that required forthermal flux annealing, described above, as multiple scans are requiredto build a film/layer. Typically, each deposited layer is between 8-10Angstroms. Required films/layers vary from 20 Angstroms for tunnel oxideused in flash memory to 1500 Angstroms for spacer applications.Therefore, the preferred scan speed is generally in the range of a fewcm/sec to about 1 msec. The preferred line width 228 is the same as thatdescribed above.

The chemical reaction is controlled by controlling: the temperature ofthe substrate surface by adjusting the continuous wave electromagneticradiation or the line of radiation; the amount and/or ratio of thegas(s) introduced into the reaction chamber; and the pressure within thereaction chamber.

The above described method can heat the substrate surface to anyreasonable temperature for a millisecond or less. In addition, as thegas right near the surface is heated by the line of radiation, thereaction of the gases only occurs at or near the surface. The heating isvery brief as the line keeps moving so only the gas right near thesurface gets to react. Because gas away from the surface never gets hot,undesirable gas phase reactions are prevented. This allows multiplegases to be injected simultaneously without leading to undesirable gasphase reactions away from the substrate surface.

In a preferred embodiment, the above described method is performed at apressure of between a few Torr to pressures above atmospheric pressure,with atmospheric pressure being preferred. FIG. 8 depicts the results ofa simulation showing that sufficient decomposition of reactants canoccur at such pressures on this short time scale. Also, in a preferredembodiment, the temperature of the line of radiation depends on thefilm/layer being deposited, but is generally in the range of 600 to 900°C.

FIG. 8 is a graph 800 of the results of a Monte Carlo simulation forsilane decomposition at 850° C. and 740 Torr, according to theembodiment of the invention shown in FIG. 6. This simulation at lowerpressures duplicates a deterministic model published by Meyerson, Scottand Tsui, Chemtronics 1 (1986) 150, which is hereby incorporated byreference.

This graph 800 shows that a silane, such as dichlorosilane (DCS), whichis a typical CVD gas, decomposes into molecules required for depositiononto the substrate surface. Decomposition occurs at 740 Torr, which isapproximately atmospheric pressure, and at a temperature of 850° C. Theoverall time in which decomposition occurs at this temperature andpressure is approximately 6×10⁻⁴ seconds. This temperature and scanspeed can only be provided by the present invention, as prior artmethods cannot achieve such a high temperature in such a short amount oftime, while providing enough time for reactions to occur.

The above described apparatus and method for depositing a layer on asubstrate has a number of advantages. For example, the thermal budget ofthe process is low due to the brief time spent at elevated temperature.

In addition, as the line of radiation only applies heat to the surfaceof the substrate, the reaction of the gases only occurs at the surface.This leads to a reduction in gas phase transport limitations. This alsoleads to a reduction in gas phase reactions away from the surface,thereby avoiding undesirable particle formation on the substratesurface. In addition, this method can be performed at atmosphericpressure, resulting in faster decomposition of reactants, such asSilane, thereby enabling high deposition rates.

FIG. 9A is a side view of yet another apparatus 900 for thermallyprocessing a substrate, according to yet another embodiment of theinvention. The apparatus 900 is similar to the apparatus 200 shown inFIGS. 2A and 2B, the apparatus 300 shown in FIG. 3, and the apparatus600 shown in FIG. 6. Like-named components are similar, except for anydifferences described below.

The apparatus 900 comprises a continuous wave electromagnetic radiationmodule 902, a stage 904 configured to receive a substrate 906 thereon,and a translation mechanism (not shown) for moving the stage 904 andcontinuous wave electromagnetic radiation module 902 relative to oneanother. The continuous wave electromagnetic radiation module 902preferably includes at least one continuous wave electromagneticradiation source 908(A+B) and optics 910(A+B) disposed between thecontinuous wave electromagnetic radiation source 908(A+B) and thesubstrate 906. As described above, the substrate 906 is any suitablesubstrate, such as a single crystal silicon substrate; silicon oninsulator (SOI); Silicon Germanium or alloys thereof; glass or quartzsubstrate with a silicon layer thereon, as used for manufacturing thinfilm transistors (TFT); or the like.

The continuous wave electromagnetic radiation source 908(A+B) is similarto the continuous wave electromagnetic radiations source 202 describedabove in relation to FIG. 2A. In a preferred embodiment, the continuouswave electromagnetic radiation source 908(A+B) provides up to 9 kW ofradiation focused by the optics 910(A+B) into a line of radiation on thesurface of the substrate that is 30 microns wide and at least 300 mmlong. Also, in a preferred embodiment, the continuous waveelectromagnetic radiation source 908(A+B) includes 15 laser diodemodules 908(A) on one side of the apparatus 900 and 16 laser diodemodules 908(B) on the other side of the apparatus 900. The laser diodemodules 908(A) are staggered in relation to the laser diode modules908(B), as illustrated in FIG. 9B, i.e., radiation emitted from thelaser diode modules 908(A) interdigitate radiation emitted from thelaser diode modules 908(B). Also, in a preferred embodiment, each set ofopposing laser diode modules is electrically coupled to one or morepower sources 916. Alternatively, each single laser diode module, orcombinations of laser diode modules, may be powered by one or more powersources. The power source(s) 916 are electrically coupled to a computersystem 914.

In a preferred embodiment, a cooling fluid, such as water, is circulatedwithin the continuous wave electromagnetic radiation source 908(A+B) tokeep it cool, as is well understood in the art.

The optics 910(A+B) include focusing optics 910(A) similar to thefocusing optics described above, and an interleave combiner 910(B). Theinterleave combiner 910(B) is described below in relation to FIG. 10,while the focusing optics 910(A) are described below in relation to FIG.11.

The apparatus 900 also preferably includes a detection module 912(A+B+C)coupled to the computer system 914, as described below in relation toFIG. 11.

The computer system 914 includes instructions and/or procedures forperforming the method described below in relation to FIG. 13.

FIG. 9C is a rear view of yet another apparatus 950 for thermallyprocessing a substrate 962, according to yet another embodiment of theinvention. In this embodiment, the line of continuous waveelectromagnetic radiation does not extend across the entire width of thesubstrate 962, but rather only partially extends across the diameter orwidth of the substrate. In other words, the line of continuous waveelectromagnetic radiation has a length 960, which is less than thediameter or width 968 of the substrate 962.

In use, the line of continuous wave electromagnetic radiation preferablymakes more than one scan across the substrate surface. Each successivescan preferably overlaps a previously scanned area, such that thermalexposure uniformity along the length of the line is improved. A lineshifting mechanism 966 is used to shift the line of continuous waveelectromagnetic radiation and the substrate relative to one anotheralong the length of the line, i.e., substantially collinear with thelength of the line and substantially perpendicular to the scandirection. This overlap averages the thermal exposure of all points onthe substrate in a similar manner to rotary averaging using in RTP.

To translate the line of continuous electromagnetic radiation relativeto the substrate, the line shifting mechanism 966 preferably translatesthe continuous wave electromagnetic radiation module (radiation source954 and the lenses 956). Alternatively, the stage 964 may be translatedrelative to the line, or both the line and the stage may be translatedrelative to each other.

Such an embodiment requires fewer laser diode modules 966, as the length960 of the line of continuous wave electromagnetic radiation needs onlyspan partially across the diameter or width of the substrate 962. Forexample, two laser diode modules may be interleaved between threeopposing laser diode modules 966.

FIG. 10 is a diagrammatic side view of the interleave combiner 910(B)shown in FIGS. 9A and 9B. The interleave combiner 910(B) forms part ofthe optics 910(A+B) and is used to improve the fill ratio of the emittedcontinuous wave electromagnetic radiation, as explained below. In apreferred embodiment, the interleave combiner 910(B) is an interleavingprism assembly.

In addition, a preferred embodiment of the apparatus 900 (FIGS. 9A and9B) includes micro lenses (not shown) to collimate the fast axis outputof each laser diode module 908(A) or 908(B). In this preferredembodiment, the pitch 1002 of each laser diode module is 2.2 mm, whilethe aperture 1004 of the fast axis collimating micro lens is 0.9 mm. Afill ratio is the area exposed to continuous wave electromagneticradiation divided by the total area of the continuous waveelectromagnetic radiation module. Therefore, for example, if the lenssystem provides a beam footprint 1 cm long by 900 microns wide, and thepitch of each laser diode module is 2.2 mm, then the fill ratio is 900microns/2.2 mm or 41%, i.e., only 41% of the emitting area of thecontinuous wave electromagnetic radiation module is actually emittingcontinuous wave electromagnetic radiation, while 59% of the space orarea on the face of the laser module remains dark. The dark areas are 1cm long by 1.3 mm (2.2-0.9) wide. This leads to substantially emptyareas where no continuous wave electromagnetic radiation is present.

In order to improve optical performance, the fill ratio is preferablyincreased by the interleave combiner 910(B), thereby requiring a smallersubsequent series of lenses 910(A) (FIGS. 9A and 9B). In a preferredembodiment, the interleave combiner 910(B) doubles the fill ratio. Forexample continuous wave electromagnetic radiation outputs from the4^(th) and 5^(th) laser diode modules are interleaved in betweencontinuous wave electromagnetic radiation emitted from the r^(d) and3^(rd) laser diode modules, as shown in FIG. 10. Accordingly, the totalpower output is that of five laser diode bars compressed into the spaceof three laser diode bars. This makes subsequent beam expansion andfocusing easier so that suitably high power densities can be achieved.

In a preferred embodiment, the interleave combiner 910(B) usesmulti-layer dielectric mirrors on a suitable optical glass, such as BK7or fused silica, for enhanced reflection at continuous waveelectromagnetic radiation wavelength.

FIG. 11 is a more detailed sectional side view of the focusing optics910(A) and the detection module 912(A+B+C). The purpose of the focusingoptics 910(A) is to focus continuous wave electromagnetic radiationemitted from the continuous wave electromagnetic radiation source908(A+B) (FIGS. 9A and 9B) into a line of continuous wave radiation onthe surface of the substrate 906. In a preferred embodiment, thefocusing optics 910(A) includes a series of seven lenses, labeled asA-G. All of the lenses A-G are preferably cylindrical lenses havingspherical, or Plano, figure. Such cylindrical lenses having sphericalfigure are selected for their relative ease, and low cost, ofmanufacture, as compared to cylindrical lenses having spherical or Planofigure shown. In addition, besides focusing the line of continuous waveelectromagnetic radiation, the totality of the cylindrical lensessignificantly reduces any optical aberrations.

Also, in a preferred embodiment, lens A is an expander lens that has asubstantially optically flat entry side and a cylindrical exit side. Theexpander lens is used to expand the continuous wave electromagneticradiation condensed by the interleave combiner 910(B) (FIGS. 9A and 9B)for subsequent focusing by the remainder of the focusing lenses B-G. Forexample, in a preferred embodiment, the beam of continuous waveelectromagnetic radiation is expanded to 20 mm wide and the fast axisdivergence is reduced to less than 0.1°. The reduced divergence makes itpossible to achieve a narrower line width. In addition, the wider beammakes it possible to achieve an acceptable working distance for a 0.4numerical aperture. Once focused by the remainder of the lenses B-G, theresulting beam is approximately 30 microns wide at the surface of thesubstrate 906.

The final lens G preferably has opposing substantially optically flatentry and exit sides, and acts merely as a quartz window to isolate thewafer environment from the lens environment. It also shifts the focussomewhat away from the radiation source.

In a preferred embodiment, the distance from the window to the substrateis approximately 8 mm. Also, in a preferred embodiment, the lenses A-Ghave the following prescription data:

-   -   Entry beam radius=2.750000; Field angle=0.250000; Primary        wavelength=810 nm

SURFACE RADIUS THICKNESS APERTURE RADIUS MATERIAL Source 0.0000001.0000e+20 4.3634e+17 AIR A_(entry) 0.000000 3.000000 4.000000 X BK7A_(exit) 7.000000 28.000000 3.000000 X AIR B_(entry) 0.000000 5.00000012.500000 X BK7 B_(exit) −23.000000 0.000000 12.500000 X AIR C_(entry)74.100000 5.000000 12.500000 AX BK7 C_(exit) 0.000000 0.000000 12.500000X AIR D_(entry) 41.000000 5.000000 12.500000 X AIR D_(exit) 119.0000000.000000 12.500000 X AIR E_(entry) 26.500000 5.000000 10.000000 X BK7E_(exit) 44.500000 0.000000 10.000000 X AIR F_(entry) 12.000000 5.0000008.000000 X BK7 F_(exit) 22.800000 3.000000 8.000000 X AIR G_(entry)0.000000 4.000000 10.000000 X QUARTZ G_(exit) 0.000000 0.000000 3.284151SX AIR Substrate 0.000000 8.420000 0.114272 Swhere radiuses and thicknesses are in millimeters. “SURFACE” refers tothe surface of the lens, where “entry” refers to the entry surface ofthe lens and “exit” refers to the exit surface of the lens. Materialrefers to the material the lens is made from. “X”, “AX” and “SX” datarefer to the shape of the aperture, rectangular or elliptical, where “X”means special aperture data, “S” means the aperture radius number in theprevious column is calculated rather than specified, “A” means anaperture stop, basically a window that rays must be able to passthrough. For example, the entry surface “AENTRY” of lens A (FIG. 11) hasa radius of 0 millimeters, i.e., is flat, a thickness of 3 millimeters,an aperture radius of 4 millimeters, has a rectangular shape, and ismade from BK7 glass. The above chart was created using Sinclair Optic'sOSLO® ray tracing software.

The lenses A-G are preferably held in place within the focusing optics910(A) by a frame 1102. In a preferred embodiment, the frame 1102 ismade from machined stainless steel. The frame 1102 also preferablyincludes some tolerances to ensure a robust system should the lenses notalign in use, where any misalignment merely shifts the line of focustowards or away from the substrate surface (or it moves laterally). Thisshift in focus is then adjusted by an automated focusing system, asdescribed below in relation to FIGS. 14A-D. In addition, during apreferred use, purge gas is pumped into the frame and through a gasinjector 1104 into spaces 1108 between the lenses to keep the lensescool. This purge gas is preferably Nitrogen, at room temperature (toavoid condensation forming on the lenses).

The detection module 912(A+B+C) preferably includes at least onereflected power detector 912(A) and at least one emitted power detector912(B). The at least one emitted power detector 912(B) is configured todetect a portion of the emitted continuous wave electromagneticradiation emitted from the continuous wave electromagnetic radiationsource 908(A+B) (FIGS. 9A and 9B), while the at least one reflectedpower detector 912(A) is configured to detect a portion of reflectedcontinuous wave electromagnetic radiation reflected from the surface ofthe substrate 906. The emitted power detector 912(B) monitors the outputof the continuous wave electromagnetic radiation source, while thereflected power detector 912(A) is used to detect reflectivity,emissivity, energy absorbed by the substrate, and/or the temperature ofthe substrate. Suitable emitted power detectors 912(B) and reflectedpower detectors 912(A) are made by Hamamatsu.

The beam splitter 912(C) is configured to sample a portion of theemitted continuous wave electromagnetic radiation by reflecting aportion of the emitted continuous wave electromagnetic radiationincident on a first substantially planar surface thereof towards theemitted power detector 912(B). In a preferred embodiment, a secondplanar surface (not shown) of the beam splitter 912(C), opposite thefirst planar surface, is used to reflect continuous wave electromagneticradiation reflected from the surface of the substrate towards thereflected power detector 912(A). The beam splitter is preferablydisposed between the continuous wave electromagnetic radiation source908(A+B) and stage 904 (FIGS. 9A and 9B). The beam splitter 912(C) isalso preferably coated with an anti-reflective coating, such as MgF. Inuse, the beam splitter 912(C) reflects or samples less than 1% of thecontinuous wave electromagnetic radiation emitted by the continuous waveelectromagnetic radiation source 908(A+B).

In use, the ratio of the detected emitted power to the detectedreflected power provides a measurement of the absorption at thesubstrate. Absorption is the process by which radiant energy isabsorbed, converted into other forms of energy, such as heat, and thenreradiated at a longer wavelength, according to Planck's Law for thermalradiation.

In a preferred embodiment, the emitted power detector 912(B) and thereflected power detector 912(A) detect continuous wave electromagneticradiation at 810 nm. Also, in a preferred embodiment, at least onereflected power detector 912(A) is configured as a temperature detectorto detect the temperature on the surface of the substrate at the line ofcontinuous wave electromagnetic radiation. To detect temperature, thetemperature detector detects continuous wave electromagnetic radiationat a wavelength other than 810 nm, such as 1500 nm. This is achieved bypositioning a filter 1106 between the reflected continuous waveelectromagnetic radiation and the detector 912(A). The filter 1106 isconfigured to allow only continuous wave electromagnetic radiationhaving a wavelength other than 810 nm to reach the detector 912(A), thusmaking it act as an optical pyrometer. This assures that the detectedsignal is a reflection signal and not an emission from the light source.In other words, only radiation that is reflected has a wavelength ofother than 810 nm. In a preferred embodiment, the filter is configuredto allow optical pyrometer operation between 900 nm and 2000 nm, with1500 nm being a preferred wavelength. This temperature measurement is,however, susceptible to emissivity variation.

The reflected power detector 912(A) and emitted power detector 912(B)also preferably include pinhole apertures to maximize the signaldetected while minimizing the collection of any stray radiation that maybe scattered within the optics due to the non-zero reflectivity of thelenses in the apparatus.

In a preferred embodiment, which includes 15 and 16 opposing laser diodemodules, 15 pairs of reflected power detectors 912(A) and emitted powerdetectors 912(B) are preferably provided. Every other reflected powerdetector 912(A) is preferably configured as a temperature detector, asdescribed above.

An alternative embodiment also includes reflectors 1110 positionedbetween the focusing optics 910(A) and the substrate 906. The reflectors1110 are configured to reflect radiation reflected from the surface ofthe substrate back to the line of continuous wave electromagneticradiation. In a preferred embodiment, the reflectors 1110 arecylindrical mirrors with center of curvature at the focus of the lens.

FIG. 12 is an isometric view of a prototype of the apparatus 900 shownin FIGS. 9A and 9B. As can be seen, a substrate, such as a semiconductorwafer, is positioned on a stage 904 within a chamber 1202. A continuouswave electromagnetic radiation module 902 is coupled to the chamber1202. In addition, a translation mechanism, such as the translationmechanism 218 (FIG. 2), moves the stage 904 relative to the continuouswave electromagnetic radiation module 902, as depicted by the arrows1206. Some of the electronics, such as the computer system 914 (FIGS. 9Aand 9B), are contained within a housing 1210. The apparatus 900 ispreferably coupled to factor interface 1208 for transferring substrates906 into or out of the apparatus 900.

FIG. 13 is a flow chart of a method 1320 for controlling a thermalprocess. Once the method 1320 has begun, as step 1322, the substrate isoriented on the stage, at step 1323, such that the subsequent directionof the scan will optimize the thermal process. This is undertaken, asdifferent orientations of the substrate have different mechanicalproperties and the yield strength may be higher in one direction thananother. In general, a notch is provided on the substrate to indicatecrystallization direction. The surface of the substrate 904 (FIGS. 9Aand 9B) may be optionally coated with a thermal enhancement layer atstep 1324. The thermal enhancement layer is made from a material havinghigh absorption properties, such as doped poly silicon or siliconnitride, on a buffer layer of oxide, and/or from a material havinganti-reflective properties. The thermal enhancement layer helps createan insensitivity to substrate surface conditions. For example, if thesurface of the substrate is highly reflective or non-uniform, thethermal enhancement layer helps maintain the substantially homogenousthermal exposure of the substrate.

The substrate is then irradiated with a line of continuous waveelectromagnetic radiation emitted from the continuous wave radiationmodule 908 (FIGS. 9A and 9B), at step 1326, thereby heating the surfaceof a substrate with a predetermined power density for a predeterminedlength of time. The predetermined power density is preferably greaterthan 30 kW/cm² (preferably 100 kW/cm²), and the predetermined time ispreferably between 100 micro-seconds and 100 milliseconds (preferablyabout 1 millisecond). This heats the surface of the substrate from anambient temperature of less than about 500° C. to a process temperatureof higher than about 700° C. The temperature at a predetermined depthfrom the surface, such as at 10 times the maximum depth of devicestructures in Si, remains below the ambient temperature plus half theprocess temperature less the ambient temperature.

As described above, the line of continuous wave electromagneticradiation may extend across the entire surface of the substrate orpartially across the substrate.

In the embodiment having reflectors 1110 (FIG. 11), any reflected orscattered light directed at the reflectors is reflected back towards theline of radiation at step 1328.

The emitted power is then measured by the emitted power detector(s)912(B) and transmitted to the computer system 914 (FIG. 9A), at step1330. The reflected power is then measured by the reflected powerdetector 912(A) and transmitted to the computer system 914, at step1332. The computer system 914 then compares the reflected power to theemitted power, at step 1334, and controls the power supplied to thecontinuous wave electromagnetic radiation source accordingly, at step1336. For example, the continuous wave electromagnetic radiation sourcemay heat different substrates differently with the same emitted power.The computer system controls power of the power source 916, which inturn may controls individual laser-diode modules, or sets of laser-diodemodules, simultaneously. In this way, individual laser-diode modules, orcombinations of laser-diode modules (or zones) may be controlled in realtime.

In an alternative embodiment, based on the measured emitted power andreflected power, the adjustment mechanism (described below in relationto FIGS. 14A-D) can adjust the height of the stage in real time at step1335. Adjusting the height of the stage can either bring the surface ofthe substrate into or out of focus, thereby controlling the powerdensity of the line of continuous wave electromagnetic radiation on thesurface of the substrate independently from the total power.

The measured reflected power and emitted power may then be used tocalculate reflectivity of the substrate, emissivity of the substrate,energy absorbed by the substrate, and/or the temperature of thesubstrate at step 1338. The reflectivity is proportional to thereflected power divided by the emitted power. A thermal emission signalfrom the wafer is measured through the optics and, optionally, throughthe interleave combiner at a wavelength longer than that of thecontinuous wave electromagnetic radiation source.

Similarly, the temperature is proportional to the adsorbed power whichequals the radiated power less the reflected power. The calculated truetemperature is derived from the difference in reflected and emittedpower subject to the calibration of the detectors. The exact method issimilar to the existing emissivity compensation schemes used for RTP, asis well understood in the art. These calculations are described in theU.S. Pat. Nos. 6,406,179; 6,226,453; 6,183,130; 6,179,466; 6,179,465;6,151,446; 6,086,245; 6,056,433; 6,007,241; 5,938,335; 5,848,842;5,755,511; 5,660,472; all of which are incorporated herein by reference.

If provided, the thermal enhancement layer is then typically removed, atstep 1340.

Furthermore, in an alternative embodiment, the thermal exposureuniformity can be improved by over-scanning Over-scanning utilizes aline of radiation that is longer than the width of the substrate. Aftereach scan, the line of radiation is shifted slightly along its length,at step 1341, such that the overall thermal uniformity is improved ifslow axis uniformity degrades over time. The shifting of the lineeffectively averages out the thermal exposure of the substrate.

FIG. 14A is a partial sectional side view of an automated focusingmechanism 1400, while FIG. 14B is a top view of a tooling substrate andstage 1414 shown in FIG. 14A, as taken along line 14B-14B′. Theautomated focusing mechanism 1400 is used to focus the line ofcontinuous wave electromagnetic radiation on the upper surface of asubstrate from the continuous wave electromagnetic radiation module 902.

The focusing mechanism 1400 preferably includes multiple photo-diodesensors 1408 embedded into a stage 1414. Each of the photo-diode sensors1408 is electrically coupled to a controller 1404. In a preferredembodiment, five photo-diode sensors 1408 are provided, however, ingeneral, there should be at least three photo-diode sensors 1408 toaccount for variations in pitch (about the X axis), roll (about the Yaxis), and height (along the Z axis), as explained below. Thephoto-diode sensors 1408 are used during the setup of the system toverify that the upper surface of the tooling substrate is in the planeof focus of the continuous wave electromagnetic radiation source.

In a preferred embodiment, a central photo-diode sensor is used to setup height, and photo-diode sensors to the left and right of the centralphoto-diode sensor are used for substantially eliminating any tilt orroll (rotation about the Y-axis) of the stage. Leading and trailingphoto-diode sensors are used to eliminate any tip or pitch (rotationabout the X-axis) of the stage. Adjustments are based upon maximizingthe signal of the photo-diode sensors.

Such verifications require a tooling substrate 1412 that is loaded ontothe stage 1414 by a substrate loading robot. The tooling substrate 1412has pinhole apertures 1410 directly above each photo-diode sensor 1410.The pinhole apertures have a smaller diameter than the width of theline, even at best focus.

The controller 1404 is also coupled to an adjustment mechanism 1402. Theadjustment mechanism 1402 is configured to raise or lower the stage 1414(along the Z axis), adjust the pitch (about the X axis), or adjust theroll (about the Y axis), as required by the controller to focus the lineof continuous wave electromagnetic radiation on the surface of thetooling substrate.

In a preferred embodiment, the adjustment mechanism 1402 includes atleast three rack and pinion drives 1406, each rotatably coupled to thestage at one end of the rack and pinion drive's screw. In use, if allthree rack and pinion drives 1406 are raised or lowered together, thestage 904 is raised or lowered. However, if individual rack and piniondrives 1406 are lowered or raised, the pitch and roll of the stage canbe adjusted. It should, however, be appreciated that any suitableadjustment mechanism 1402 may be used.

The controller 1404 is also coupled to the translation mechanism 218 formoving the continuous wave electromagnetic radiation source 908(A+B) andthe stage 904 relative to one another.

FIG. 14C is a flow chart 1420 of a method for automatically focusing aline of continuous wave electromagnetic radiation on an upper surface ofa substrate. Once this method is started at step 1422, a toolingsubstrate 1412 (FIG. 14A) is positioned on the stage, at step 1424. Thecontinuous wave electromagnetic radiation source 908(A+B) then radiatesa first photo-diode sensor 1408, at step 1426, such as the centralphoto-diode positioned below the center of the tooling substrate. Thefirst photo-diode sensor provides the measurement used for absoluteheight adjustment. The first photo-diode sensor measures the intensityof the continuous wave electromagnetic radiation, at step 1428, andtransmits this intensity to the controller 1404. The controller theninstructs the adjustment mechanism 1402 to adjust the height of thestage, at step 1430. The height is adjusted by the adjustment mechanismraising or lowering the stage 904 along the Z axis until the line oflight is in focus at the aperture in front of the first photo-diodesensor.

The controller then instructs the translation mechanism to translate thecontinuous wave electromagnetic radiation module and the stage relativeto one another, at step 1431, such that the next photo-diode is alignedwith the line of radiation. The next photo-diode sensor 1408 (FIG. 14A)is then irradiated at step 1432. The intensity of the continuous waveelectromagnetic radiation at this photo-diode sensor is measured, atstep 1434, and transmitted to the controller 1404. The controller theninstructs the adjustment mechanism 1402 to adjust the pitch and/or rollof the stage by tilting the stage about the X and Y axes, as necessary,to ensure that the line of light is in focus at this photo-diode sensor,at step 1436. The controller then determines, at step 1438, whether thesetup has been completed, i.e., whether measurements have been takenfrom all the photo-diode sensors. If the method is not completed(1438-No), then the radiation module and stage are translated relativeto one another until the next photo-diode is aligned with the line ofradiation and the next photo-diode irradiated at step 1432, and themethod repeated until such time as the line of light is in focus at allpoints along the surface of the substrate. If the method has completed(1438-Yes), then the process is completed at step 1440.

This process may be either iterative, or, alternatively, complete scansin the Z direction can be made for all detectors prior to adjustment. Inthis way, the plane of the tooling wafer will become known to the systemrelative to the plane of focus. At that time, the three servos make theappropriate adjustments to make the two planes coincident.

In a preferred embodiment, after the height has been adjusted, tilt orroll is eliminated using the left and right photo-diode sensors, whichwill come into and out of focus at different heights if the stage istilted or rolled. Once tilt or roll is eliminated, the substrate ismoved to a leading edge photo-diode sensor and another through focusdata-set is collected. Pitch or tip is zeroed out when the centralphoto-diode sensor and the leading edge photo-diode sensors have thesame through focus data at the same heights. The trailing edgephoto-diode sensors are used for verifying that the stage is, indeed,level.

FIG. 14D is a graph 1450 of the measured energy density (NormalizedSignal) 1454 versus the height of the stage 1460, with zero being atbest focus, at an aperture 1410 (FIG. 14A). Through focus is shown as1452. As can be seen, when the line of light is focused at the aperture,at 1456, the energy density is the highest. Also shown is the spot size,i.e., the area over which the energy is spread. The spot is anillustration of where the image of the laser diodes is in the plane offocus. In order to simplify analysis, rotationally symmetric lenses areassumed, i.e., a spot, and not a line, is used for analysis. In actualuse, however, the spot is preferably a long line with a width thatspreads.

Accordingly, the focusing mechanism 1400 (FIG. 14A) assures a good focusfor all substrates. It also allows thermal recipes to vary the linewidth without having to resort to movable optics, i.e., the powerdensity at the surface of the substrate can be adjusted independently byadjusting the height of the stage without adjusting the total poweroutput from the continuous wave electromagnetic radiation source.

Furthermore, any of the above described systems, apparatuses, or methodsmay be used with an implanter or Plasma Doping (PLAD). Also, theabove-described methods may be used for back end thermal processes thatrequire using a high power continuous wave electromagnetic radiationlaser source operating in or near the UV. Once such back end thermalprocess is copper reflow, where wavelengths produced by such a lasersource are strongly absorbed by most materials, including copper.

In addition, the above described apparatuses and methods may be used forisotropic etching and/or ashing, such as etching photoresist off asubstrate surface. Such isotropic etching and/or ashing does not requirethe use of a plasma, and, therefore, does not have any of the associatedproblems of plasma damage, such as those caused by hot electrons.

What is more, the above described apparatuses and methods may be usedfor all flat panel anneals. Current laser recrystallization processesraster a laser spot across the surface of the flat panel.Recrystalization generally proceeds radially, thereby making the speedand overscanning critical process control variables. Using the presentinvention, however, recrystallization proceeds from a broad, continuousfront, resulting in the formation of larger grains due to the reduceddegree of freedom for recrystallization. In the present invention,recrystallization can only occur in front of and behind the line ofradiation, making the scan speed an important variable.

Still further, the above described apparatuses and methods may be usedto activate the substrate junction beyond an a-c/Si interface to improvep-n junction leakage, where a-c is an amorphous-crystalline interface. Aproblem with present annealing methods is that not all defects at anoriginal a-c interface are annealed out. These defects are theend-of-range (EOR) defects for an amorphizing implant. If these defectsremain in the junction where voltage must be sustained (depletionregion), then the regular array assumption for Silicon is less thanperfect and leakage will occur. In the present invention, however, thethermal exposure can be made long enough to move the junctiondeeper—past the EOR defects. Pulsed lasers are not well suited to dothis, as due to the short pulse lengths well below a microsecond, nodiffusion can occur.

The foregoing descriptions of specific embodiments of the presentinvention are presented for purposes of illustration and description.They are not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Obviously, many modifications and variationsare possible in view of the above teachings. For example, although onebeam splitter is described herein for reflecting continuous waveelectromagnetic radiation towards both the reflected power detector912(A) and the emitted power detectors 912(B), more than one beamsplitter may be used. The embodiments were chosen and described in orderto best explain the principles of the invention and its practicalapplications to thereby enable other skilled in the art to best utilizethe invention and various embodiments with various modifications thatare suited to the particular use contemplated. Furthermore, the order ofsteps in the method are not necessarily intended to occur in thesequence laid out. It is intended that the scope of the invention bedefined by the following claims and their equivalents. In addition, anyreferences cited above are incorporated herein by reference.

1. A laser light source emitting radiation in a processing beam ofsufficient intensity to thermally process a substrate, comprising: aplurality of first laser diode modules arranged along a first directionand emitting respective first laser light beams on respective paths inparallel to a second direction; a plurality of second laser diodemodules arranged along a direction parallel to the first direction andemitting respective second laser light beams on respective paths inparallel to a third direction anti-parallel to the second direction,wherein the first and second laser diode modules are staggered withrespect to each other such that the first and second light beam areinterdigitated; and a combiner receiving the first and second laserlight beams and combining them into the processing beam and directingthem to be parallel to a fourth direction perpendicular to the first andsecond directions.
 2. The source of claim 1, wherein each of the firstand second diode modules emit a plurality of first and second laserlight beams respectively arranged along the fourth direction.
 3. Thesource of claim 1, further comprising a plurality of cylindrical opticallenses arranged along the fourth direction and receiving the combinedfirst and second laser light beams.
 4. The source of claim 1, whereinthe combiner includes at least one multi-layer dielectric minor.
 5. Thesource of claim 4, wherein the combiner includes a plurality ofmulti-layer dielectric minors.
 6. The source of claim 1, wherein thecombiner comprises an interleaving prism assembly.
 7. The source ofclaim 1 configured as a radiation source for a thermal processing deviceto process the substrate with a scanned line beam as the processingbeam.
 8. The source of claim 1, wherein the plurality of first andsecond laser diode modules are arranged respectively side by side inrows extending along the first direction.
 9. The source of claim 1,wherein the first and second light beams are all of a same opticalwavelength.
 10. A laser light source, comprising: at least one laserlight module emitting a plurality of laser light beams parallel to afirst direction and spaced in a first sequence along a second directionperpendicular to the first direction; and an interleave combinerreceiving the laser light beams and deflecting them parallel to thesecond direction and spaced in a second sequence which is interleavedfrom the first sequence.
 11. The source of claim 10, wherein theinterleave combiner comprises a plurality of multi-layer dielectricmirrors extending obliquely to the first and second directions andreflecting different ones of the laser light beams emitted by each ofthe at least one laser light module.
 12. The source of claim 10, whereinthe interleave combiner comprises an interleaving prism assembly. 13.The source of claim 10, comprising a plurality of the laser lightmodules arranged along a third direction perpendicular to first andsecond directions, wherein the interleave combiner receives the laserlight beams from all of the laser light modules.
 14. The source of claim13, wherein the plurality of the laser light modules are disposed onopposed sides of the interleave combiner and emit their respective laserlight beams in anti-parallel directions.
 15. The source of claim 10,further comprising a plurality of cylindrical-optical lenses arrangedalong the second direction and receiving the deflected laser lightbeams.
 16. The source of claim 15, wherein some of the optical lenseshave flat sides.
 17. The source of claim 10 configured as a radiationsource for a thermal processing device.
 18. A laser light source,comprising: a laser diode module emitting along a first direction afirst sequence of emitted laser beams spaced apart in a second directionperpendicular to the first direction; and an interleave combinerincluding a plurality of reflective surfaces receiving different ones ofthe emitted laser beams and reflecting them in a second direction into asecond sequence of reflected laser beams spaced apart and interleavedfrom the first sequence.
 19. The light source of claim 19, comprising afirst plurality of such laser diode modules and interleave combinersspaced along a third direction perpendicular to the first and seconddirections.
 20. The light source of claim 19, comprising a secondplurality of such laser diode modules and interleave combiners spacedalong the third direction and emitting output laser beams anti-parallelto those of the first plurality of such laser diode modules andstaggered therewith.
 21. The light source of claim 18, wherein thereflective surfaces comprise multilayer dielectric minors.
 22. A laserlight source, comprising: a plurality of laser diode modules which arearranged along a first direction and each emit a plurality of laserlight beams of a same optical wavelength parallel to a second directionoblique to the first direction and spaced in a first sequence along athird direction oblique to the first and second directions; and aninterleave combiner receiving the laser light beams and deflecting themto be parallel to the third direction and spaced along the seconddirection in a second sequence which is interleaved from the firstsequence.
 23. The source of claim 22, wherein the interleave combinercomprises a plurality of multi-layer mirrors extending obliquely to thesecond and third directions and incorporated into a prism assembly.